Traffic on the Internet has grown dramatically over the last decade and continues to grow. Routers play a critical role in sustaining that growth. Data to be passed by routers is generally divided into a series of packets that can be transmitted between devices. Packets include control information and payload data. The control information corresponds to information used by a communication network to deliver the payload data. For example, control information can include source and destination network addresses, error detection codes, packet sequencing identification, and the like. Typically, control information is found in packet headers and trailers included within the packet and adjacent to the payload data.
Generally, routers can operate with two primary functions or planes. The first function corresponds to a control plane, in which the router learns the set of outgoing interfaces that are most appropriate for forwarding received packets to specific destinations. The second function is a forwarding plane, in which the router sends the received packet to an outbound interface.
To execute the forwarding plane functionality, routers can maintain a forwarding information base (“FIB”) that identifies, among other packet attribute information, destination information for at least a subset of possible network addresses, such as Internet Protocol (“IP”) addresses. In a typical embodiment, the FIB corresponds to a table of values specifying network forwarding information for the router. To execute control plane functionality, routers can maintain a routing information base (“RIB”) that identifies routes through the network. The RIB can also contain metrics associated with those routes. As the router receives route updates, the router can update the RIB with announced or withdrawn routes. Generally, where the RIB identifies available routes, the FIB identifies an output interface corresponding to a selected route and the FIB is typically generated from information in the RIB.
Different protocols can be used to update the FIB and RIB. For example, an Open Shortest Path First (OSPF) routing protocol can be used, as well as other routing protocols. Generally, communications between the routers is limited to topology-based descriptions that describe the router landscape in a nearby area.